Human-to-Human Transmission of Severe Fever With Thrombocytopenia Syndrome Resulting in Fatal Cases: A Case Series

Severe fever with thrombocytopenia syndrome (SFTS), primarily a tick-borne disease, can also cause fatal human-to-human transmission. This report analyzes a cluster of six SFTS cases identified in China in 2022, involving one index patient and five secondary infections, with an overall mortality of 83%. All secondary cases occurred in elderly individuals (aged 66-85 years) following unprotected exposure to the index patient's body fluids during bedside care or traditional postmortem rituals, without documented tick bites. The high fatality rate underscores the potential severity of secondary transmission, particularly among elderly adults. More critically, this outbreak exposes systemic delays in early diagnosis even within an endemic area, highlighting fundamental gaps in the clinical management of undifferentiated fever. Effective prevention, therefore, relies on establishing a clinical system for early detection, rapid diagnosis, and prompt isolation while implementing culturally adapted community interventions to reliably interrupt transmission.